Heat Index Calculator
Estimate how hot it feels based on temperature and humidity.
How to use
Uses the Rothfusz regression used by the US National Weather Service (valid mainly for warmer conditions).
Frequently asked questions
Why is heat index important?
High humidity reduces the body’s ability to cool through sweating, raising heat stress risk.
Do you store the numbers I enter?
Calculations run in your browser. Inputs are not sent to our servers.